Method of locating natural gas.



w U u F. sQUmEs.- METHOD 0F LOCATING NATURAL GAS.

APPLICATION FILED APH. 19| 1915.

Patented J an. 18, T916;

WITNESSES The coLuMmA PLANOGRAPH C0., WASHINGTON. D. c.

i E STAT WLS PATENT OFFICE.

FREDERICK SQUIR-ES, OF MCCONNELSVILLE, OHIO, ASSIGNOR TO VTALTERSQUIRES, OF ZANESVILLE, OI-IIO.

METHOD OF LOCATING NATURAL GAS.

Application filed April. 19, 1915.

To all whom t may concern:

Be it known that I, FREDERICK SQUIRES, a citizen of the United States,residing at McConnelsville, in the State of Ohio, have invented certainnew and useful Improvements in Methods of Locating Natural Gras, ofwhich the following is a specification, reference being had to theaccompanying drawings, forming a part hereof.

This invention seeks to cover broadly a method whereby natural gas maybe recovered at much less expense than heretofore, and may be dividedroughly into two interrelated steps, the first of which is concernedwith the locating' of gas bearing strata and the second of which isconcerned with the recovery of the gas from such strata. In thisspecification, for the sake of clearness, it has been elected todescribe these two steps separately so that a full understanding of thepractice of the improved method in connection with each may be had,although it will appear that these two steps are so interrelated and themeans for and manner of carrying each into effect are so similar', thatthey constitute, for the operator in the gas fields, a single method.

In the development of gas properties the operator is, of course, firstconcerned with the securing of land which he can satisfy himself withreasonable certainty, will give forth natural gas on a paying basis.Accordingly the first step in the improved method seeks to teach theengineer how he can determine with reasonable certainty, the area of agas bearing stratum, the approximate outline of such area, and thegeneral direction of flow of the gas therein whereby predictions as tothe character of adjoining property can be made. Heretofore, 1t has beenthe practice for an operator to lease a tract of land and try it out forgas rbearing strata by sinking a great number of wells, each well beingdrilled without regard to the location of every other well except in thematter of distance. The expense and inefficiency of this makeshiftmethod is fully appreciated by those skilled in the art and yet nopracticablel way of determining the required information through thesinking of only a few wells, has been available. Again, an owner orlessee of oil or gas property usually carries on spotted drillings inwhich the locations are remote from the boundary of the tract, so thatthe-owners Specification of Letters Patent.

Patented J an. 18, 1916.

Serial No. 22,523.

of the adjoining tracts will receive no indication of pay areas on theirproperties as the result of operations of their neighbor. Obviously, ifoil or gas was gotten from a well sunk near a boundary, the adjacentproperty holder would know immediately that his land also probablycontained a pay area. By the present method, all such unde-` servedadvantages are eliminated and it is made possible for an operator tolocate pay areas through wide tracts. For instance, an operator cansecure leases of many contiguous tracts of land and sink perhaps asingle well near the center of each tract and determine between whichwells oil or gas bearing strata lie, the approximate areas of suchstrata and the general directions in which they extend so thatprofitable locations for other drillings can be predicted.

The step of the improved method which is now under consideration can beemployed to equal advantage in connection with either oil properties orgas properties although, inasmuch as the method generally is concernedwith the recovery of natural gas, the description will be given inconnection with gas properties. In accordance with this step of themethod, two or more wells are sunk at relatively remote points withrespect to each other, the distance between the wells being far greaterthan that commonly employed in what are termed locations where the wellsare about two hundred feet apart. It has been found, in actual practice`that the locations of the wells which must be sunk for use in practisingthe present invention can range from 900 to 2,000 feet distant one fromanother, thereby effecting a saving which may be represented by theratio of 2,000 to 200, in the number of wells, that is, about ten wellsin the preliminary stages of development.

After the two or more wells have been sunk, fluids, having distinctivephysical or chemical properties, are introduced into one or more wells,usually under pressure, and observations made at one or more of theother wells, to detect the presence of such fluids. Air will serve thepurpose. In this method, it should be noted, advantage is taken of thegeological fact that oil and gas bearing strata are porous in theirnature, oil usually being found in sand and gas being found in coal orthe like, and of the further fact that the porous stratum is completelyinclosed by a nonporous stratum of deposits, such as slate, etc. Whenthe fluid referred-to is introduced through one well into the porous oilor gas bearing stratum, its escape from such stratum can only beeffected through one of the other wells, it being entrapped and directedin its travel by the nonporous walls of slate or the like.

if the tests referred to, indicate the presence of the testing fluid atone or more of those wells which are remote from the well through whichthe fluid is introduced, it is a reasonable deduction that the fluid hastraversed a porous oil or gas bearing stratum (depending upon whetherthe well sunk terminated in an oil or bearing stratum), and that thestratum thus traversed lies between the point of introduction of the gasand the point of its escape. lf trie testing fiuid cannot be detected atany well, then it is equally certain that it has been interrupted in itsflow between the point of introduction and such well by reason of thediscontinuance of the porous stratum. The results obtained in the mannerbriefly pointed out will indicate at once just where other wells are tobe located to yield gas or oil on a paying basis.

As will appear hereinafter the invention is not to be limited to thecharacter of the testing fluid or to the character of the tests fordetermining the continuity of the porous stratum.

Another feature of the first step of the improved method which can bepractised conveniently during the carrying on of' the test referred to,is the determining of the general direction in which the located strataextend, with respect to the drilled wells. In making this determinationthe pressure of' the testing fluid at two or more of the wells is takenand these pressures will show whether the fluid tends to seek anyparticular well by reason of a ready passage afforded by an extensiveporous stratum lying beyond it (as will be the case where the pressureis relatively great).I or whether the testing fiuid reaches the well ata relatively low pressure, thus indicating that the stratum terminatesat a point very near to such well. From these observations the operatorwill be able to predict with reasonable certainty the general outline ofthe areas of porous strata and the general directions in which theyextend, thereby insuring that all drillings subsequently made willstrike pay strata and not result, in the usual hit and miss method nowemployed, in the costly location of many dry wells.

Another method by which the direction of the extension of a field can bedetermined in accordance with the present invention resides in apressure test depending` upon the volume of compressed fluid retainednear any particular well. For instance,` pressure is applied to all ofseveral wells in a field until meters at each well indicate uniformpressure throughout the field. IThe pressure creating apparatus is thenremoved and readings taken from volume meters at each well. rThe metershowing the greatest reading will indicate the direction in which thegreatest amount of the pressure fluid is escaping and by this thedirection in which the field extends.

The second and very closely interrelated step of the improved methodwill nou7 be outlined briefly. As noted before, this part of the methodis peculiarly useful in connection with increasing the productiveness ofnatural gas wells, particularly those wells which are drilled intostrata having gas under relatively low pressure or in which the pressureof the gas has been lowered materially by the escape thereof. No succes.ful method has yet been devised for recovering more than a certainpercentage, by volume, of gas to be found in any given lield, thepressure of the entrapped gas being depended upon for the ventingthereof. Under this practice, each shaft is operated as a unitindependently of all other drillings in the neighborhood and, as hasbeen pointed out before, the drillings are determined by a hit and missmethod and without regard to the probable location of the gas bearingstratum.

By the improved method, after the wells referred to in the descriptionwith respect to step one, lave been drilled and the tests incident tothe step have been made and such other wells located as may be desired,the gas is permitted to vent itself under its own pressure until suchpressure becomes insufficient for continued flow. The apparatus whichmay have been used in connection with the first step for forcing thetest fluid into the stratum under pressure may then be applied to one ortwo or more wells which have been shown to communicate with 5.2;

a porous stratum and a suitable fluid under high pressure is forced intothe stratum. The effect of this introduction of fluid under pressure isto drive the natural gas from all parts of the porous stratumto one ormore of the wells communicating therewith and cause it to escape untilthe particular stratum to which the pressure is applied is completelyexhausted of gas. The fluid used may be either liquid or gaseous and maybe such as is determined to be best adapted under the particularconditions although, in practice, air has been found to serve thepurpose satisfactorily. This step of the method is not to be limited tothe introduction into the porous stratum of a fluid under pressure butcan be carried out by any chemical or physical means for creatingpressure within the porous stratum, and in such relation to the gascontained therein combustible miXture might A be introduced andcombustion then brought about by some convenient means, the resultingproducts of combustion serving to set up the desired pressure. Othermodifications of this step and other ways of practising it successfullywill be pointed out more particularly hereinafter in connection with thedetailed description and the general scope of the entire method will bedefined in the appended claims.

Reference is now to be had to the accompanying drawings which indicatein a very simple manner an arrangement of suitable apparatus and wellsfor practising the improved method.

In these drawings-Figure l is a View in section of two wells sunkthrough the earth to a gas bearing stratum, one of the wells beingprovided with means for introducing a liuid under pressure into theporous stratum and the other well being equipped with an escape pipe forthe entrapped gas. Fig. 2 is a purely diagrammatic representation ofthree wells so located with respect to each other as to enable theadvantages of the improved method to be realized when employed inconnection with them.

In order to maintain the arrangement proposed in the preamble, the twosteps of the improved method will be described independently, in so faras it is possible, and accordingly reference will first be made to F ig.2 of the drawings for a description of the manner of locating oil or gasbearing strata, determining approximately the areas of such strata andsecuring indications of the general direction in which such strataextend for the purpose of predicting proper locations for additionalwells.

It may be supposed, first, that the tract of land, indicatedconventionally in Fig. 2, is owned by an operator and `that he desiresto vdetermine at just what points on this land, if any, wells should besunk. In following the present method, a well A will be sunk at anyconvenient point and a second well B will be sunk at a relatively greatdistance therefrom, perhaps anywhere from 900 to 2000 feet, although itis to be understood clearlv that this invention is notconcerned with thedistances between wells. The operator after sinking the wells to theporous gas bearing Stratum C, shown in Fig; 1, will `or may communicatewith any desired point,

as will be understood. The porous stratum C in which the gas is found iswalled in solidly by strata H of impervious minerals, such as slate,etc. By the arrangement of apparatus described and the geologicalformation of the strata H with respect to the porous stratum C, acontinuous communication is formed between the compressor G and theoutlet of the pipe E. Accordingly, if a fluid is forced from thecompressor Gr into the porous stratum C, it will traverse theintervening space between the lower ends of the wells A and B and escapethrough the outlet pipe E. If this fluid be one having distinctivephysical or chemical properties, such as of taste, color, odor,inflammability, etc., its presence at the outlet E can be readilydetected in due time. Air will serve the purpose. If this presence isdetected, then the operator can feel reasonably certain that there is agas bearing stratum C extending from the well A to the well B and thathe can sink wells between these two and recover gas on al paying basis.Such tests and resulting information will obtain with any well, such asI, sunk at some distance from both the wells A and B. The outlet fromthe well I can be tested by liuids introduced at A and other fluidsintroduced at B, so that it can be determined readily whether there is acontinuous gas bearing stratus between the wells A and I and another gasbearing` stratum between the wells B and I. Three wells have beenillustrated in the accompanying drawings as it will be appreciated thatby reason of their triangular disposition with respect to cach other arelatively great tract of land can be tested. at a relatively slightexpense and locations for many intermediate wells determined. Given thcwells A, B and I the following test will determine the direction of thestratum beyond them. It is to be noted that many gas and oil bearingsands exist in connected pools or long narrow streaks. Applyr the samepressure at all the wells A, B and I and after a sufiicient time haselapsed to place the stratum under pressure take readings from volumemeters at cach well A, B and I. The meter showing the greatest readingwill determine the direction in which the greatest amount of thepressure fluid is escaping and by this the direction in which thestratum extends from the triangle A, B, I. Again, the use of three wellsin the manner described enables the approximate area of the gas bearingstratum to be determined within the limits of the territory bounded bythe three wells. Of course, the preliminary development may be extendedby sinking additional wells in other directions, and the improved methodcarried on with respect to such additional wells. lVhenever it is foundthat the distinctive fluid introduced at one well cannot be detected atanother well, it can be concluded that the porous stratum is interruptedat some point between the wells and that drillings cannot be carried onbetween them to advantage. Another point to be emphasized is that theinvention is not to be limited to the use of liquids or ofases of anyparticular character where a fluid is used in the manner hereinbeforereferred to and that other ways can be employed for determining thecontinuity of the porous stratum between any two wells. Again, a gasmight be introduced which would combine with the natural gas to form acombustible mixture and the combustible nature thereof determined bybringing the mixture into contact with igniting means at the point ofescape. Inflammability would indicate that the gas has traversed thespace between the wells, while, if the union expected were not formed,then it would be known that the gas had not been able to traverse suchspace and the continuity of the stratum was broken. Electricalemanations may be made to enter and traverse a proper fluid introducedinto the porous stratum and detected at test wells or where a conductivefluid, such as salt water, is present, a current may be passed throughit and the continuity of the stratum thereby established.

A useful application of this first step of the present method will befound where it is supposed that the wells A, B and I are on separatetracts of land. In such a case, the operator might obtain short termleases of these three tracts at relatively little expense and sink thethree wells A, B and I and carry out the tests above described. Fromthesetests he would be able to ascertain whether the land between thewells were worth drilling or whether it was not worth while to take overany one of the separate tracts.

Another feature of this first step of the method resides in the meansfor determining the probable direction in which a gas bearing stratumextends with respect to any well.

y lVhere a fluid under pressure is introduced at the well A and escapesfrom the wells B and I, the pressure and direction of motion at thesetwo last named wells could be determined in any convenient manner andthat well which showed the higher pressure would be the one nearer tothe larger portion ofthe stratum. If under these circumstances it werefound that the well I showed a higher pressure, thon it would bereasonable to conclude that other drillings in the neighborhood of thewell I would be more productive than drillings near the well B, thepressure at which indicates that the gas bearing stratum terminates at apoint somewhere near this well. An active motion through and beyond thewell B would indicate that the area beyond the well B would beproductive.

The second step of the improved method is concerned with the recovery ofthe gas after the stratum C has been located and is practised wheneverthe gas within the stratum is at such a low pressure as to beinsuflicient to vent the gas or where this pressure has been somaterially reduced by venting of the gas that it is necessary to impressan artificial pressure on it to force it from one of the escape wells Bor I. In accordance with the method, a fluid is introduced into thestratum C through the well A by the compressor G and permeates theentire stratum, thereby impressing a pressure upon the entrapped naturalgas. The gas, under the influence of the artificial pressure, seeks toescape and finds its only outlet at the wells B, I, where it may berecovered. In this step of the method, as in the one first described,the invention is not to be limited to the character of the fluid used,whether liquid or gaseous, nor is it to be limited to the use of a uidunder pressure introduced as described. In practice it has been foundconvenient to use compressed air at high pressure and satisfactoryresults have been obtained. If preferable, however, a gas such as airmay be introduced into the natural gas which will combine therewith toform an explosive mixture. When this mixture is ignited the products ofcombustion will force the natural gas throughout the stratum C to escapefrom the wells B and I. Other means for attaining the same end byemploying the present invention will suggest themselves to those skilledin the art.

From the description given, it will be apparent that the improved methodconsists essentially in the locating of two or more wells so situatedwith respect to each other as to make it possible to carry on operationsor tests from one to another, which will give the results moreparticularly stated in the preamble. The many variations in the methodhereinbefore indicated may be practised without departing from thespirit of the invention, as may many others not particularly referredto, provided that all such variations fall within the scope of theappended claims.

I claim as my invention:

l. The method of determining the location and probable direction ofextent of gas or oil bearing strata which consists in sinking three ormore wells to such strata at relatively remote points, creating anartiicial pressure at one well which shall be observable at the otherwells when the Wells communicate with a common stratum, and recordingthe pressures at all of the wells, whereby the general direction of flowof the fluid in the stratum is indicated.

2. The method of determining the proper direction of extension of gas oroil bearing strata, which consists in sinking two or more wells to anoil or gas bea-ring stratum,

FREDERICK SQUIRES.

Signed in the presence of- H. T. CARTER, T. E. MGELHENNY.

Copies of this patent may be obtained for ve cents each, by addressingthe Commissioner of Patents, Washington, D. C.

